The present invention is an adapter card for a workstation or personal computer for receiving any of the Ethernet, Token-Ring, or Asynchronous Transfer Mode (ATM) protocols, and automatically determining which protocol is presently active and the speed at which it is operating.
Historically, numerous protocols have evolved for local area networks (LANs). Three of the most popular protocols are Ethernet, Token-Ring, or Asynchronous Transfer Mode (ATM). The diversity of protocols has created a problem for manufacturers of electronic equipment, such as computers, file servers, hubs, printers, and like equipments that connect to LANs. The problem is how to build hardware to attach workstations to the local area networks that is compatible with a plurality of protocols. In recent years, the problem has been further complicated by the introduction of a second higher performing versions of the Ethernet, Token-Ring, or Asynchronous Transfer Mode protocols. Ethernet now operates at 10 MHz rates (called 10 Base-T) and 100 MHz rates (called 100 Base-TX), Token-Ring operates at either 4 or 16 MHz rates, and ATM operates at either 25 or 155 MHz rates.
One simple solution to the problem, which has been implemented in the prior art, is to manufacture a different pluggable card type to support each of the different network protocols and speeds. The user would buy the type of pluggable card required to interface with the network protocol that was available in his office or building. This is not an ideal solution, because the vendor requires more development funds and a larger inventory of parts, while the user buys an inflexible solution and also requires a larger inventory of parts. The industry has evolved to more flexible solutions using a single card type that has automatic detection of the protocol type and speed. This is possible, because a standardized connector has evolved which requires the protocols of interest to be standardized to the same physical connector called RJ-45. FIG. 1 shows the RJ-45 contact assignments and how they differ for the protocols of interest.
In U.S. Pat. No. 5,574,722, “Protocol Independent Switch” by Slykhouse et al., Slykhouse teaches a method for automatically determining the network protocol, either Token-Ring or Ethernet, for a network hub or concentrator. Slykhouse uses the RJ-45 pin connections as shown in FIG. 1 and teaches hardware for listening for a frame on specific pins to differentiate between Token Ring or Ethernet. The present invention uses the RJ-45 pins to help in the automatic determination of the LAN protocol being used but, in addition, requires recognizing the media access control (MAC) layer protocol differences. The present invention requires a more complex mechanism for automatic protocol determination because of the additional ATM protocol and additional speed selections allowable for Ethernet and ATM. The present invention is not an obvious extension of Slykhouse's method but involves media speed/encoding detection hardware and active transmission of test frames which loopback to the sender and are non-intrusive in nature. This is vastly different than Slykhouse's passive listening method. The present invention also differs from Slykhouse in the field of application. Slykhouse provides a method for network protocol detection in the networking infrastructure device (hub or concentrator), while the present invention is for an adapter card in a workstation.
In U.S. Pat. No. 5,249,183, “Interfacing Unit for Local Area Networks” by Wong et al., Wong teaches a mechanism for an Ethernet adapter to provide attachment to a traditional Ethernet coaxial network or an Ethernet twisted pair (10 Base-T) network. The adapter automatically selects the network that is active by first checking for activity on the 10 Base-T network by sensing the presence of link integrity pulses. If the 10 Base-T network is inactive, it then uses the coaxial network. The approach for detecting Ethernet activity (presence of link integrity pulses) is the same listening approach used in the present invention. Detection allows the adapter to select the appropriate Ethernet media to use. However, Wong applies only to selection of the appropriate physical media specifically for an Ethernet network, whereas the present invention applies to selection of the appropriate protocol used by the network, that of Token-Ring, Ethernet, or ATM.
Wong's method is passive, but the present invention involves media speed/encoding detection hardware and active transmission of test frames which loop back to the sender and are non-intrusive in nature.
In U.S. Pat. No. 5,142,528, “Protocol Selector and Protocol Selection Method” by Kobayashi et. al., Kobayashi teaches a mechanism for two stations which support multiple protocols to negotiate the protocol to be used. Generically, this is accomplished through the use of an independent communication port over which the protocol to be used by the primary communication port is negotiated. Kobayashi also teaches the specific case of negotiating B channel protocols over the D channel of an Integrated Services Digital Network (ISDN) link. This does not relate to the present invention in that no independent communication channel exists for determining or negotiating the protocol used by the primary channel. The present invention deals with determining the operational protocol of a LAN network in a non-disruptive manner and then attaching to the network. Negotiation of the operating protocol is not part of the process.
In U.S. Pat. No. 5,497,460, “System and Method for Determining Network Connectivity” by Bailey et al., Bailey teaches a mechanism for providing automated detection of the LAN protocol for a network interface card in a workstation that supports multiple protocols. The automated detection mechanism in the workstation detects the protocol utilized by the networking infrastructure device to which the workstation is attached. This is the same problem solved by the present invention. Bailey's method differs in that the process proposed by Bailey can be disruptive, and the present invention is non-disruptive. Bailey detects the protocol by sending a logical link control (“LLC”) frame—which is a potentially disruptive process. The present invention does not send any frames which may be disruptive during the protocol detection process. In addition, the transmission of LLC frames proposed by Bailey is applicable only to Ethernet and Token-Ring but not for ATM. The present invention provides detection for Ethernet, Token-Ring, and ATM.
In U.S. Pat. No. 5,442,629, Token Ring Speed Detector” by Geyer et al., Geyer teaches a method and apparatus for determining LAN speed for Token-Ring LANs by choosing between the two standard Token-Ring speeds: 4 MHz and 16 MHz. Geyer's method applies only to Token-Ring. Geyer's teachings are applicable to the present invention in that Geyer's method is used directly to supplement the present invention by determining at what speed the Token-Ring is operating after the present invention determines that the connected LAN is Token-Ring. Geyer differs from the present invention in that it does not provide automatic determination of the LAN type from amongst three candidates: Ethernet, Token-Ring, and ATM.
In U.S. Pat. No. 5,530,842, “Generic Backplane System Which Is Configurable to Serve Different Network Access Methods Simultaneously” by Abraham et al., Abraham teaches a mechanism for supporting multiple protocols over a generic backplane of a communications hub or concentrator. Separate modules, which are protocol and physical network specific, are still provided for attaching to the appropriate LAN network. Abraham's invention is specific to the implementation of a hub backplane which, in essence, is a proprietary LAN network. It does not specifically address the attached protocols, i.e., protocols can be translated or encapsulated within the backplane network of Abraham. The backplane network must carry all protocols of the attaching networks, it does not need to specifically and completely conform to any one of the networks. The present invention is for devices attaching to standard LAN networks where the attaching device must specifically and completely conform to the attaching network, and the present invention provides the mechanism for doing so.
In IBM Technical Disclosure Bulletin, Vol 29, No 2,. July 1986, the article, “Method to Establish a Network Connection Dynamically,” teaches a method of connection setup at the Network Layer of the protocols. The article applies to a different protocol layer and has no relation to the present invention which addresses LAN operation at the MAC and physical (PHY) layers.
In IBM Technical Disclosure Bulletin Vol. 29, No. 9, February 1987, the article “ECL Reconfiguration Using a Circuit Switch,” teaches a method for configuring switches for internal port to port connections. It does not provide for the configuration of protocols. It is therefore not related to the present invention but applies to the configuration of LAN hardware.
In U.S. Pat. No. 5,568,525, “System and Method for Connection of Multiple Protocol Terminals” by de Nijs et al., de Nijs teaches a mechanism for automated network configuration. De Nijs differs from the present invention in that de Nijs provides network configuration at the networking infrastructure device. The present invention provides network configuration at the user workstation. In addition, de Nijs uses a mechanism of detection of protocol based on characteristic impedance of the transmission media. This is different from the present invention's detection mechanism, which is based on PHY/MAC layer of Ethernet, Token-Ring, and ATM.
In U.S. Pat. No. 5,586,117, “Method and Apparatus Which Allows Devices with Multiple Protocol Capabilities to Configure to a Common Protocol Configuration” by Edem et al., Edem teaches an automatic determination method for Ethernet only to distinguish between the 10 and 100 MHz versions. Edem teaches a scheme using clock pulses to match configurations between a workstation and a network infrastructure device. Edem's method differs from the present invention in that it does not provide a mechanism to distinguish between differing LAN protocols.
In European Patent 577,435 A1, “Common Interface for a Communication Network” by Hutchison et al., Hutchison teaches a common interface for Ethernet only. Hutchison teaches a mechanism to distinguish between Ethernet interfaces-Attachment Unit Interface (AUI) or 10 Base-T. Hutchison differs from the present invention in that Hutchison does not provide a mechanism to distinguish between differing LAN protocols.
Japanese Publication 06-085848 teaches the detection of 10Base-T Ethernet vs. Integrated Services Digital Networks (ISDNs). The scheme taught in the publication is to use a filter to distinguish the signal frequency (10 Mb vs. 56 Kb). The Japanese publication differs from the present invention in that it does not use pin assignments or protocol information. The Japanese publication also differs from the present invention in that it does not consider Token-Ring or ATM.
It is a further object of this invention to provide a LAN adapter that detects whether the network connection of a workstation is Ethernet, Token-Ring, or ATM, and adapts automatically to the type and speed of the attached network.
It is a further object of this invention to provide protocol type and speed detection using active transmission of test frames on a non-disruptive basis that does not affect the operation of the network in relation to other attachments during the protocol search process.
It is an object of this invention to provide a single apparatus for the support of multiple LAN protocols where several different speeds options are supported for each of the multiple protocols and that this detection occurs in an optimal sequence (i.e., most likely conditions are detected first in order to minimize setup time for the user).